It is a common characteristic of most hitherto known float controlled valve assemblies used for monitoring and influencing the liquid level of receptacles that a flow passage of a valve means is altered by a displaceable closure member. The closure member is generally movable between two end positions associated with an open and a closed state of the valve means, respectively. Such known valve assemblies also have a definite mechanical linkage between the float and the closure member of the valve means which is moved, at least in certain phases of the changes in the liquid level of the receptacle, by the float. A known valve assembly of the kind indicated is described for example in U.S. Pat. No. 5,072,751, where a float is secured to the end of a longer arm of a single-arm lever capable of tilting around a fulcrum secured to a valve housing, and the closure member of the valve is assigned to the end of a shorter arm of the single-arm lever in a way that an upper end of the closure member is permanently pressed by the pressure of water flowing across the valve against the lever while said lever is driven between its two end positions by the float in both directions. As a result of this, during filling up or refilling the receptacle after discharge, the movement of the closure member in the closing direction of the valve slows down gradually and proportionally to the gradually slowing rate of the rise of the float. Thus, the time period needed for filling or refilling the receptacle is extremely long, and the closure member of the valve narrowing the flow passage of the valve gradually over such long periods of time, as well as the co-acting valve seat are subject to rapid wear. This is an inherent and major disadvantage of the type of known valve assemblies referred to and dealt with e.g. in U.S. Pat. No. 5,072,751.
Patent specifications EP-A-768487, EP-A-709607, U.S. Pat. No. 5,230,361, FR-A-1223714 and GB-A-2067271 disclose float controlled valve assemblies in which a spring mechanism between a pivoted balance lever and a closure member of a valve means provides for self-locked states of the balance lever and thus, said closure member of the valve means in both a first and a second end position of said closure member corresponding to a closed and a thoroughfare state of the valve, respectively. In addition to this, the mechanism has a snap-action function in both directions of movement between said first and second end position for quick opening/closing of the valve. In these known prior art approaches however, for initiating the snap-action of the mechanism in both directions, the respective self-locked states of its end positions must be overcome by exerting a definite torque load, acting on the balance lever in the one sense of rotation in the first end position and acting on said balance lever again, in the opposite sense of rotation in the second end position of the closure member of the valve. Consequently, the balance float(s) of the valve assembly must be connected-to the balance lever of the valve via a rigid linking member e.g. a rod which must be capable of bearing and transmitting both, tensile and compressing load. This characteristic feature of the known valve assemblies of self-locking and snap-action function involves the disadvantage that due to the necessity of maintaining a rigid linkage between the balance float(s) and the balance lever of the assembly, the valve means cannot be located at any remote or distant location from the receptacle, it must rather be arranged within or at least in the nearest proximity of the liquid receptacle. Thus, with the known valve assemblies cited and listed further above, a "remote control" of the liquid level of receptacles can not be performed without using known additional means of signal and/or power transmission.